倒披针叶虫实种内功能性状的变异特征及对种群稳定的影响

The characteristics of intraspecific functional traits variation and their effects on population stability of Corispermum lehmannianum

倒披针叶虫实(Corispermum lehmannianum)在古尔班通古特沙漠呈优势分布,其重要值仅次于梭梭(Haloxylon ammodendron)和白梭梭(Haloxylon persicum)。本研究在古尔班通古特沙漠选择标准样地,通过不同坡位的定点观测,从种内功能性状变异与种群稳定关系的角度,分析倒披针叶虫实种群维持机理。结果表明:(1)该物种种群内存在广泛的性状变异:在时间尺度上,株高、冠幅变异系数随生长发育先增加后降低;在空间尺度上,在同一坡位灌木树冠覆盖区域变异显著高于裸地区域(P<0.05);不同坡位种群对比发现,除萌发期外,坡顶种群性状及变异与其他坡位种群均存在显著差异(P<0.05)。(2)种内变异受不同坡位环境强烈的影响,坡位对种群密度与萌发现象的影响显著:坡顶种群密度最小,萌发数量最少;坡中密度最大,萌发数量最多;萌发率与死亡率均随时间变化降低。综合研究表明,在干旱荒漠区,倒披针叶虫实种群稳定主要受不同坡位、不同树冠覆盖度等微生境的强烈影响,种内功能性状变异表现出对荒漠环境的良好的适应性,对种群维持也起着重要作用。

Corispermum lehmannianum is the dominant specie in the Gurbantunggut Desert, and its importance was next to the Haloxylon ammodendron and Haloxylon persicum. We studied the relationship between intraspecific functional trait variation and the stability of the population, and analyzed the mechanism of the population persistence through the observation of the permanent quadrats at different partitions in dune. The results showed that there was a common intraspecific trait variation(ITV) in the population. The coefficient of variation(CV) of plant height and canopy area increased first and then decreased during the growth. On the spatial scale, the CV under the shrubs' canopy areas was significantly higher than that in the bare area at the same dune partition(P<0.05). The value as well as the CV of plant height and canopy area at the top of the dune was significantly different from that at other partitions except germination period(P<0.05). The ITV was strongly influenced by different slope positions, there were significantly differences in population density and germination among different dune partitions. The population density and germination quantity were minimum at the top of the dune, but were maximum at the middle of the dune, both germination and mortality decreased with time. The results highlight that the population stability of C.lehmannianum is strongly affected by microenvironment such as different slope positions and different canopy coverage in arid desert area, and the intraspecific trait variation plays an important role for plants to adapt to the desert environment and contributes to the population persistence.